It may be useful to look at Zn powder additive behavior in sliding ,
https://www.researchgate.net/publication/234135295_Alloying_contact_zones_by_metallic_nanopowders_in_sliding_wear?ev=prf_pub
Article Alloying contact zones by metallic nanopowders in sliding wear
ZnO can be broken down into Zn and O by the heat generated during friction of steel plates. Both Zn and O are solvable in Fe and can form a variety of intermetallics with other alloying elements in steel.
Zinc's affinity to oxygen is much higher that of iron and also thre is a lot of oxygen in the air to oxidize iron. So my point is that when adding ZnO to the lubricant you can hardly decompose it in sliding as it happens for example in case of ZDDP. Most plausible is the situation when ZnO will mix with iron oxides generated in sliding and form a composite oxide layer. At least when experimenting with brass nanopowder additives we always found ZnO on the worn surface together with Cu-enriched layer. It means that Zn formed the oxide by coming out of the brass.
@ Sergei Tarasov
Sir, the problem is in my EDS result no Zinc was observed.Moreover, the pins after pin on disk test showed an increase in weight. The only increase is in percentage of Carbon. Kindly let me know you opinion.
I assume carbon comes from the lubricant, at least it is always found on the worn surfaces. Also EDS has not good accuracy with respect to carbon content. The problem is that you can not find zinc. This may happen by several reasons. The first will be too low concentration of ZnO in the lubricant, I believe it is at the level of 0.05-0.1 wt% in the lubricant and it then goes down in sliding by removal of wear debris. Another reason may be that ZnO has low adhesion to the steel and therefore flushed off the worn surface. Third reason is that ZnO particles are too heavy or agglomerated and settle down on the bottom of a chamber instead of the worn surface. Forth one is that ZnO is decomposed chemically by the lubricant constituents and Zn became dissolved in it.
As to the pins gaining extra weight after the test. How much is the gain? I remember somebody suggested that such an effect is due to oxidation. It may be worthwhile to evaluate the content of oxygen on the worn surfaces. However, EDS again is not the best method to do it.
What about the pin's heigth? Has it changed and, if yes, how much? It here any lip formation at the periphery of the pin's worn area? What happened to the disk track?
As discussed Zn might have formed an composite layer, but EDS could not efficiently detect it. Can you try XPS to find out the presence of Zn on the worn pin surface.
- Badges
- Science topic
- Similar topics
- Mathematics
- Algebra
- Matrix